abandoned abstract accident admittance ammunition anti anti-burglary anti-theft army assault attack background bank banking blast blastproof bomb bombs building bulletproof bunker burglary closed cold concept concrete construction danger dangerous deepearth defence device door doors dug dug-out empty entrance entry explosion explosive fallout fight fort fortification game games green handle heavy history insurance intro iron lock locked metal metaphor military nuclear object old out private proof protect reinforced safe safety secret secure security shelter stain stained storage strategy strong symbol theft trust underground unlock war warfare weaponry weapons westerplatte